Media for cell growth and method for making them

Abstract

Aqueous solutions of partial hydrolysates of algae, optionally labelled with stable isotopes, are used as growth media for cells.

We claim: 
     
       1. A process for preparing an algal-based hydrolysate which comprises: (a) forming an aqueous slurry of algae,   (b) rupturing the cell walls of said algae,   (c) adding to said algae sufficient acid to partially hydrolyze proteins in said algae, such that the resultant hydrolysate comprises 35%-50% by weight small polypeptides and 22%-30% amino acids, the resultant hydrolysate comprising an acid-soluble fraction and an acid-insoluble fraction,   (d) discarding the acid-insoluble fraction of the hydrolysate,   (e) removing acid from the soluble fraction until the fraction has a pH of at least 1.0, and   (f) titrating the hydrolysate with a base to convert any remaining acid in the hydrolysate to a salt and adjust the pH of the hydrolysate to within the range of about 6.5 to about 7.0.   
     
     
       2. The process of claim 1, wherein the algae has been labelled with one or more stable isotopes. 
     
     
       3. The process of claim 1, wherein the resultant hydrolyzate is dried. 
     
     
       4. The process of claim 2, wherein the isotopes are selected from  2  H,  13  C,  15  N and  17  O. 
     
     
       5. The process of claim 1 or 2, wherein the hydrolysate is formed into an aqueous solution useful for supporting growth of bacterial, yeast or fungal cells, the aqueous solution further comprising one or more salts and buffers which provide additional nutrients for cell growth. 
     
     
       6. The process of claim 5, wherein the buffer is phosphate buffer. 
     
     
       7. The process of claim 5, wherein the salts are selected from ammonium chloride, sodium chloride, calcium chloride, magnesium sulfate, iron sulfate, and inorganic salts of manganese, molybdenum, copper, cobalt and zinc. 
     
     
       8. The process of claim 1, wherein the acid is added to the algae to form an acid concentration of about 2 to about 3M. 
     
     
       9. The process of claim 1, wherein the acid is selected from HCl and sulfuric acid and trifluoroacetic acid. 
     
     
       10. The process of claim 1, wherein the acid is HCl. 
     
     
       11. The process of claim 1, wherein the base is selected from NaOH, KOH, Ba(OH) 2  and BaCO 3 . 
     
     
       12. The process of claim 1, wherein the acid is HCl and the base is NaOH. 
     
     
       13. The process of claim 1, wherein the algae is selected from species of Chlorella, Neochloris, Navicula Scenedesmus, Spirulina, Chlamydomonas, Porphoridium and Dunalliela. 
     
     
       14. The process of claim 13, wherein the algae is Chlorella vulgaris. 
     
     
       15. The process of claim 5 wherein the hydrolysate comprises about 0.25% to about 10.0% of the solution. 
     
     
       16. A nutrient medium for the cultivation of bacterial yeast or fungal cell cultures prepared by a process which comprises: (a) growing algal cells,   (b) forming an aqueous slurry of the cells,   (c) disrupting the cells to produce a cell lysate,   (d) subjecting the cells or cell lysate to acid hydrolysis under conditions that result in incomplete hydrolysis of cellular proteins to produce a partial hydrolyzate; the hydrolysate comprising an acid-soluble fraction, which comprises about 35% to about 50% by weight small polypeptides and about 22% to about 30% amino acids, and an acid-insoluble fraction;   (e) discarding the acid-insoluble fractions;   (f) removing acid from the soluble fraction until the fraction has a pH of at least about 1.0 and then titrating the fraction with a base to within the range of about 6.5 to about 7.0,   (g) optionally adding one or more trace minerals or nutrients to the partial hydrolyzate.   
     
     
       17. A nutrient medium for the cultivation of bacterial, yeast or fungal cell cultures prepared by a process which comprises: (a) growing algal cells which have been labelled with at least one stable isotope,   (b) forming an aqueous slurry of the cells,   (c) disrupting the cells to produce a cell lysate,   (d) subjecting the cells or cell lysate to acid hydrolysis under conditions that result in incomplete hydrolysis of cellular proteins to produce a partial hydrolysate, the hydrolyzate comprising an acid soluble fraction, which comprises about 35% to about 50% by weight small polypeptides and about 22% to about 30% amino acids, and an acid insoluble fraction,   (e) discarding the acid insoluble fraction,   (f) removing acid from the soluble fraction until the fraction has a pH of about 1.0 and then titrating the fraction with a base to within the range of about 6.5 to about 7.0,   (g) optionally adding one or more trace minerals or nutrients to the partial hydrolysate.   
     
     
       18. An algal-based hydrolysate which comprises: (a) about 35 to about 50% by weight polypeptides,   (b) about 22 to about 30% amino acids,   (c) about 5 to about 15% sugars and reducing sugars and   (d) about 7 to about 15% water.   
     
     
       19. The hydrolysate of claim 18, which comprises: (a) about 40 to about 45% by weight polypeptides;   (b) about 24 to about 28% by weight amino acids;   (c) about 5 to about 15% by weight sugars and reducing sugars, and   (d) about 7 to about 15% by weight water.   
     
     
       20. The hydrolysate of claim 17, made from algae which has been labelled with one or more stable isotopes. 
     
     
       21. The growth medium of claim 16 or 17, supplemented with glucose, glycerol or fructose. 
     
     
       22. A substrate for supporting bacterial, yeast or fungal cell growth which comprises an aqueous solution of the hydrolysate of claim 18, said hydrolysate comprising about 0.25 to about 10% of said substrate. 
     
     
       23. A process according to claim 5, wherein the aqueous solution formed is useful for supporting bacterial cell growth. 
     
     
       24. A program according to claim 5, wherein the aqueous solution formed is useful for supporting yeast cell growth. 
     
     
       25. A process according to claim 5, wherein the aqueous solution formed is useful for supporting fungal cell growth. 
     
     
       26. A substrate for supporting bacterial cell growth which comprises an aqueous solution of the hydrolysate of claim 18, said hydrolysate comprising about 0.25 to about 10% of said substrate. 
     
     
       27. A substrate for supporting yeast cell growth which comprises an aqueous solution of the hydrolysate of claim 18, said hydrolysate comprising about 0.25 to about 10% of said substrate. 
     
     
       28. A substrate for supporting fungal cell growth which comprises an aqueous solution of the hydrolysate of claim 18, said hydrolysate comprising about 0.25 to about 10% of said substrate.